how do you get rid of the messy black or corrupted faces?
Erm … can you post a pic? (hard to tell what you’re talking about)
But there are a few things I can think of that you might be talking about. It might be that you have two faces on top of each other which will give you funny looking rendered faces (to fix, try “remove doubles”). Or if you’re using subsurf and set smooth, sometimes you get strange looking faces. To fix that, try selecting the faces that look strange and press ctrl+N (to fix normals)
Hope that helped you 
cool, i didn’t think about that, thank you. (couldn’t post a pic, this is a library’s cpu) , but thanks anyway.